OK, first off, as far as compression is concerned, you don't say WHAT you are wanting to squash. The way that Lexicon is designed, the compressor was designed to be used on the front end of the processor, to act as a leveller BEFORE the effects processing. This isn't a bad idea, as a lot of folks have found that a bit of compression before a 'verb or delay is helpful to keep the effect(s) at a consistent level, and aids in preventing digital 'overs' at the front end. I would use it that way.
BUT if you're thinking:"Gee, I can have reverb on 1 Aux, Delay on another (yes), and also have a couple of compressors for snare and kick (or whatever)"...I wouldn't bet on that. Even if it IS possible to do it with the (4) channels of processing available, the dynamics section is a bit of a compromise, and there is the issue of latency to contend with. Stick with a hardware compressor, especially if you are on a budget... You can find good used dbx 166 or 266 models used for $100-200, and they are indispensable. By the way, if all you have is a single 2-channel unit, try to put them on the "wilder" elements of the band(s)-usually the screaming singers. Putting one across the stereo mix output can be very counter-productive, especially with a pounding bass and/or kick drum.
Now, as far as the reverb is concerned, you really can't go wrong with a Lexicon. Personally, I use an MPX550 (discontinued, I believe) because the sound is good and the thing is solidly built. And there is no wall wart to fall out of the power slot when the thing is carted around. Plus, it is reasonably easy to edit on-the-fly.

For a delay, I like a dedicated box, which is a bit of a problem, because there are few on the market. TC makes one (or two), but their cheaper stuff has been a problem for me. Instead, I use a Roland SDE3000 (or an
SDE1000, have both). Sure, they're older than dirt, the converters are less than pristine, and they only have a handful of user presets. BUT they sound great for live, they are easily edited and recalled, they are built like a tank, and that flourescent display is just 'way too cool. Not to mention the fact that these were the first units to have Tempo Tap(footswitchable, no less!). And if you can't find a 1000 or 3000 (the difference is their available delay time), you can find the SDE2000, which has the same editable parameters, but no display or presets. There's one at my local GC for around $150.00.
You might also look at the Yamaha SPX line. You can find the veritable SPX90II for around $100. and it makes a good dedicated delay as well as a plethora of other effects (including 'verbs and pitch-shifting). But, like I said, I would get seperate boxes for the reverb and delay. So instead of a 4-channel everything-in-a-box, you might want to consider a 2-channel reverb, a seperate delay line, and then a couple of comps. Not only will you get more bang, but your full rack will look even cooler !!

Thanks a million for this - extremely helpful and informative piece of advice.

As for what gonna get squezeed - I was thinking drumkit... I am lucky - no badly screaming vocals at the moment, just a nice one :)

The band I work with play jazzy stuff BUT there is quite a rock-like punch to it every now and then. The drummer uses hihat, OHs and just touches the drums but then he kicks the bassdrum big time and starts hammering on the snare and toms. So I move sliders up when he is quiet and, quite hastily, down, when he changes the style. It happens very often, I feel too often to control other things. I was thinking grouping all drum tracks to stereo and compressing it would save me a lot of hassle.

I think I got the idea, I'll check ebay again and try to avoid all-in-one despite it is so tempting. One thing puzzled me a bit in your reply:

moonbaby wrote: the dynamics section is a bit of a compromise, and there is the issue of latency to contend with. Stick with a hardware compressor

Again: apologies, I never really worked with outboard processors so this might be silly to ask:

You mean the lexicon would have software compressor same as dbx VST plugins? Is this why there would be latency? Or is that because when you use multiple effects on multieffect processor, simulatnously, some latancy might occur?

What I mean is this: anytime there is audio changed from analog>digital there is a slight delay. Whenever you reach for a knob to adjust something, it's really too late. Live sound is a totally different situation(AMINAL!!) (Mis-spelling indended to emphasisize!)...
Also. something that I did not mention: I use the return of the delay line as another source, like a singer or sax player, whatever. You bring it in to another channel, just like another vocalist or soloist. Now you can adjust that delayed singer/soloist into the mix accordingly THEN route THAT signal to the 'verb, floor monitors,etc. Does that make sense?
Years ago (many, I'm 52!!!), this was done to make use of the HAAS effect, the use of a slight delay to change one's perception of sound location. I used to use the original Eventide Clockworks 1949 Harmonizer on the soloists in .38 Special, the AWB, and this whacko bass player, Jaco Pastorius, to "bring out" elements of the mix for radio broadcasts. It's not enough just to push up the fader(s). All you do is pump the dynamics in an unmusical way. Use the delay as an "ear tricker". By slightly delaying the sound you want the audience to follow as a soloist, you are avoiding the pitfalls of simply "jacking up" the gain on that channel. The meters hardly jump, but the solo does! It's like magic!!!

Thank you.
Delay line jumped to #2 on my shopping list now just after the reverb unit
I guess compressors will have to wait..
I am really grateful for your replies and looking for a button here
to action some bourbon delivery
:wink:

for the record, i have a Lexicon MX400 for sale...

it's more than i need.

Rockstar:
You should put that box up on the "Buy and Sell" so that others can check it out.
Hartmut:
Compressors are great on certain sources, including snare and kick, but from what you're describing, I can tell you that they can create more problems than they solve. You might have to re-think your mic placement. Also, have you discussed this issue with the drummer? Explain to him that he needs to play the way he wants to sound. All you should be doing is accurately capturing that, with a minimum # of mics. A compressor can help to keep slight fluctuations in dynamics in check. It will also increase drum ringing, cymbal "hang time", and kick "boom". Choose thy tools wisely...